Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 127 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/SmallStrings.cpp b/Source/JavaScriptCore/runtime/SmallStrings.cpp
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+++ b/Source/JavaScriptCore/runtime/SmallStrings.cpp
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+/*
+ * Copyright (C) 2008, 2010 Apple Inc. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "SmallStrings.h"
+
+#include "HeapRootVisitor.h"
+#include "JSGlobalObject.h"
+#include "JSString.h"
+#include <wtf/Noncopyable.h>
+#include <wtf/PassOwnPtr.h>
+
+namespace JSC {
+
+static inline void finalize(JSString*& string)
+{
+    if (!string || Heap::isMarked(string))
+        return;
+    string = 0;
+}
+
+class SmallStringsStorage {
+    WTF_MAKE_NONCOPYABLE(SmallStringsStorage); WTF_MAKE_FAST_ALLOCATED;
+public:
+    SmallStringsStorage();
+
+    StringImpl* rep(unsigned char character)
+    {
+        return m_reps[character].get();
+    }
+
+private:
+    static const unsigned singleCharacterStringCount = maxSingleCharacterString + 1;
+
+    RefPtr<StringImpl> m_reps[singleCharacterStringCount];
+};
+
+SmallStringsStorage::SmallStringsStorage()
+{
+    LChar* characterBuffer = 0;
+    RefPtr<StringImpl> baseString = StringImpl::createUninitialized(singleCharacterStringCount, characterBuffer);
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
+        characterBuffer[i] = i;
+        m_reps[i] = StringImpl::create(baseString, i, 1);
+    }
+}
+
+SmallStrings::SmallStrings()
+{
+    COMPILE_ASSERT(singleCharacterStringCount == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
+    clear();
+}
+
+SmallStrings::~SmallStrings()
+{
+}
+
+void SmallStrings::finalizeSmallStrings()
+{
+    finalize(m_emptyString);
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i)
+        finalize(m_singleCharacterStrings[i]);
+}
+
+void SmallStrings::clear()
+{
+    m_emptyString = 0;
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i)
+        m_singleCharacterStrings[i] = 0;
+}
+
+unsigned SmallStrings::count() const
+{
+    unsigned count = 0;
+    if (m_emptyString)
+        ++count;
+    for (unsigned i = 0; i < singleCharacterStringCount; ++i) {
+        if (m_singleCharacterStrings[i])
+            ++count;
+    }
+    return count;
+}
+
+void SmallStrings::createEmptyString(JSGlobalData* globalData)
+{
+    ASSERT(!m_emptyString);
+    m_emptyString = JSString::createHasOtherOwner(*globalData, StringImpl::empty());
+}
+
+void SmallStrings::createSingleCharacterString(JSGlobalData* globalData, unsigned char character)
+{
+    if (!m_storage)
+        m_storage = adoptPtr(new SmallStringsStorage);
+    ASSERT(!m_singleCharacterStrings[character]);
+    m_singleCharacterStrings[character] = JSString::createHasOtherOwner(*globalData, PassRefPtr<StringImpl>(m_storage->rep(character)));
+}
+
+StringImpl* SmallStrings::singleCharacterStringRep(unsigned char character)
+{
+    if (!m_storage)
+        m_storage = adoptPtr(new SmallStringsStorage);
+    return m_storage->rep(character);
+}
+
+} // namespace JSC